An isolated spinal demyelinating lesion is very rare and almost always associated with multiple sclerosis. There are only a few reports of biopsy or resection of MS-associated lesions. Sometimes the radiological and the histopathological findings can lead to a false diagnosis of a tumour. A 15-year-old girl presented with a progressive spastic tetraparesis and various associated clinical symptoms. Magnetic resonance imaging (MRI) suggested a possible intramedullary tumour extending from C4 to C7 and the need for surgical intervention. There was no previous neurological or other history and the brain MRI was normal. The performing surgeons based their procedures on oncological criteria. The extracted lesion was finally diagnosed as a demyelinating plaque. The postoperative course was uneventful without deterioration of the neurological status and the young patient improved completely after 4-months of rehabilitation. After an 8-year follow-up, the patient remains in remission and free of neurological defects. Apart from the radiological findings, the CSF exam as well as the evoked potentials does not suggest a diagnosis of MS. A demyelinating plaque in the cervical spinal cord can occasionally imitate a cervical intramedullary tumour leading to an operation. Such lesions underscore the sensitivity of present-day lesion detection procedures. An addition of a MS work up could be beneficial in some cases of intramedullary tumours without a typical history, although in the case presented this type of workup was negative.